88 GMC SIERRA 1500, 90K MILES

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88GMC1500
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  • 2 POSTS
A MECHANIC SAID MY TRUCK WAS IDLING HIGH. MY QUESTION IS, HOW CAN I ADJUST THIS? CAN I DO IT MYSELF OR DO I HAVE TO GO TO A SHOP? I'D RATHER DO IT MYSELF.
May 10, 2006 at 9:31 AM
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LOSONE
  • ✓Experienced Mechanic
  • 1,616 POSTS
1st when the engine is warm, shut it off and remove the IAC motor from the side of the throttle body. It is the largest thing on the side.

Clean it good with carb cleaner also the inside where the IAC sits.

Reinstall, start the engine and let the idle settle.
Unplug the IAC motor

adjust the manual adjustment (near the throttle arm) to 400-450 RPM.

Reconnect the IAC motor. Let the idle settle.

Turn off the truck.

Disconnect the battery to clear the check engine light

Drive the truck for about 5 miles so the computer can match the new base idle setting.

When you stop it should idle correctly.

NEVER ADJUST THE MANUAL SCREW UNLESS YOU FOLLOW THIS PROCEDURE.

Let me know and we'll go from there
May 10, 2006 at 9:40 AM
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